It actually activates some javascript that sometimes shows some extra text on the pages, like this:

http://img802.imageshack.us/img802/7347/switchbackmappack.png

Can you spot the text? No? Let me clear it up for yah:

http://img855.imageshack.us/img855/5584/switchbackmappackmarked.png

This finally makes sense of something I spotted earlier on the TU details page:

http://img191.imageshack.us/img191/2879/sandtrapannounced.png

Lets make this clearer:

http://img89.imageshack.us/img89/2528/sandtrapannouncedmarked.png
Sandtrap?

I haven't been able to find a release date yet, but it might show up in later posts.
I can't wait for sandtrap :O

If you guys can find anything on any other posts that'd be great, because I haven't been able to check them all yet (too damn lazy).